Regioregular polyester

Interesting results have been reported recently for a regioregular polyester obtained by self-polymerization of an hydroxy-acid chromophore in mild conditions (Fig. 2.23) [94]. 

In addition, synthetic approaches and general properties of regioregularly ring substituted aromatic polyesters are described in this report ... 

The regioregularly substituted polyester RR-BB was prepared via the following multistep routes as described in Experimental ... 

The most contrasting feature in the thermal properties of ordered sequence or regioregularly substituted polyesters, when compared with those of the cor- responding random counterparts, is their much higher melting temperatures, Tm. For example, Tm of OS-10-8 is higher by 85 C than Tm of RS-10-8 251 vs. 166 C. 

The dependence of Ti values on regioregularity of substituents is not so much clear, partly due to lack of enough data. Very often Ti values of wholly aromatic polyesters are so high that the polymers tend to undergo thermal decomposition before reaching isotropization temperature, which makes the comparison more difficult. 

Multi-step synthetic routes have been devised for the preparation of thermotropic, sequentially ordered copolyesters and regioregularly ring substituted polyesters. 

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